| The objective of this research is to develop an improved magnetic suspension system for ultra precision motion control and to demonstrate its feasibility in the area of nano-technology via two applications, namely nano-imprinting and nano-metrology. In order to increase the travel range in horizontal axes and to reduce mechanical vibrations in the formerly developed magnetic suspension system, both actuation scheme and laser measurement systems are modified. Adaptive control and disturbance observer were employed to compensate model variations due to varying airgaps in DC electromagnets and to achieve uniformly high precision motion control throughout the workspace of the system.; In the first application, a nano-metrology system consisted of an optical pick up head from a compact disc drive and the magnetic suspension system was developed. As the optical pick up head is a 1D probe, the magnetic suspension system was employed as a precision motion control scanning stage to obtain surface geometry of miniature objects having 21/2D features. Experiment results demonstrated that the developed metrology system can provide nano-meter measurement resolution over several millimeters range. In the second application, a nano-imprinting procedure was employed to fabricate miniature pores on a polymer membrane. In order to produce high aspect ratio, nano-sized pores over a large area, a nano-imprinting unit was developed to facilitate the process, along with the developed magnetic suspension system incorporated into the procedure to provide precise position and orientation control. System integration has been performed and preliminary experiments have been performed to show the feasibility of the process. |
